Search

This study was made to determine the effects of bloodmeal mass and oviparity in Aedes albopictus (Skuse) (Diptera: Culicidae) on continued host-seeking activity in female mosquitoes and efficacy of the repellent N,N-diethyl-3-methylbenzamide (DEET). There was a curvilinear relationship between bloodmeal mass in partially fed Ae. albopictus and host avidity with a threshold between 0.8 and 1.0 mg of ingested blood for reduced host seeking by female mosquitoes. Egg development and fecundity were related to bloodmeal mass, which also evoked significantly different mean host seeking rates in nulliparous and parous Ae. albopictus. The repellency of DEET to partially blood fed female mosquitoes depended on oviparity status and host avidity with repellent failure soonest in partially blood fed nullipars.

Mosquito species abundance and composition estimates provided by trapping devices are commonly used to guide control efforts, but knowledge of trap biases is necessary for accurately interpreting results. We tested the hypothesis that commercially available traps (Mosquito Magnet-Pro, the Mosquito Magnet-X) would be significant improvements over the CDC Miniature Light Trap with respect to abundance, species diversity, and measures of recruitment in a wooded area of the Bronx Zoo in New York City, NY. The Mosquito Magnet-Pro collected significantly more mosquitoes (n = 1,117; mean per night, 124 +/- 28.3) than the CDC Miniature Light Trap (n = 167; mean per night, 19 +/- 5.5). The Simpson's diversity index was greatest for the Mosquito Magnet-Pro. A CDC light trap from a simultaneous surveillance project was located 15 m away and used as a control trap to test for significant differences in mosquito counts on nights with or without the experimental traps. There were no significant differences between nights, indicating the test traps did not recruit beyond 15 m. The traps differed significantly in abundance, but they had similarly limited sampling areas. Measured differences in abundance were independent of differences in diversity. This study highlights how differences between traps might affect species abundance and composition estimates.

Purpose: Efforts to provide medication assistance to the rural poor in central Louisiana are described., Summary: The Central Louisiana Medication Access Program (CMAP) began functioning in 2001 with the objective of providing medication assistance and medication education to the rural poor in the community. The program serves individuals who use the outpatient clinic at the state-run public hospital in central Louisiana. Patients receive prescription drugs for a variety of chronic conditions, paying only a processing fee of dollar 3 per prescription, with a maximum outlay of dollar 15 per visit. A pharmacist counsels the patients about their medications. The medications are funded both through the program and through assistance programs run by pharmaceutical companies. A total of 5307 patients were enrolled in the CMAP between May 2001 and March 2003, and they received over 140,000 prescriptions at a cost saving to them in excess of dollar 2.5 million., Conclusion: The CMAP has been able to provide prescription medications and medication counseling to needy patients in a rural environment at little cost to them.

The repellency of different concentrations (5, 10, 25, 50, 75, and 100%) and combinations of 5 essential oils (Bourbon geranium, cedarwood, clove, peppermint, and thyme) to Aedes aegypti (L.) and Anopheles albimanus Wiedemann when applied to human skin was determined in laboratory tests. Cedarwood oil failed to repel mosquitoes and only high concentrations of peppermint oil repelled Ae. aegypti. None of the oils tested prevented mosquito bite when used at the 5 or 10% concentration. Thyme and clove oils were the most effective mosquito repellents and provided 1 1/2 to 3 1/2 h of protection, depending on oil concentration. Clove oil (50%) combined with geranium oil (50%) or with thyme oil (50%) prevented biting by An. albimanus for 1 1/4 to 2 1/2 h. The potential for using essential oils as topical mosquito repellents may be limited by user acceptability; clove, thyme, and peppermint oils can be irritating to the skin, whereas both human subjects in this study judged the odor of clove and thyme oils unacceptable at concentrations > or = 25%.

A triple cage olfactometer for evaluating mosquito attraction responses is described. The olfactometer is designed for easy access for interior cleaning, has a mechanism that allows synchronous operation of the port doors on each cage, and requires 0.8 m2 of floor space. It is constructed of clear acrylic, contains 3 test chambers in a tiered configuration, has paired removable sleeves and mosquito traps on each cage, and is equipped with a filtered external air supply system that has temperature and relative humidity control.

Laboratory bioassays assessed differences in the protection time provided by the repellent deet (N,N-diethyl-3-methylbenzamide) against 5-d-old nulliparous and 10-, 15-, and 20-d-old nulliparous and parous female Aedes aegypti (L.), Anopheles albimanus (Weidemann), and Anopheles quadrimaculatus Say sensu lato. Mean protection time was shortest against An. albimanus (1.6 h) and An. quadrimaculatus (1.5 h) and longest against Ae. aegypti (6.5 h), but was not significantly influenced by mosquito age or parity. Mean percentage of biting at repellent failure time was highest in An. albimanus (14.2%), followed by An. quadrimaculatus (7.0%) and Ae. aegypti (2.9%), was higher in parous females (10.8%) than in nulliparous females (5.9%), and was highest overall (35%) in 20-d-old parous An. albimanus. Interaction between mosquito species and parity and between parity and age factors, respectively, resulted from a significant decrease in percentage of biting by parous An. quadrimaculatus compared with other females, and a significant increase in biting by 20-d-old parous females compared with other females. The main finding of this study is that repellent protection time is unaffected by parity; this is important because parous mosquitoes are the primary target of personal-protection measures in disease-endemic areas. When repellent failure did occur, there was a higher risk of bite by old, parous An. albimanus than for any other species, age, or parity grouping of females.

Seven microorganisms including 4 protozoans, 2 fungi, and a bacterium infected Aedes albopictus (Skuse) larvae collected from 12 counties in northecentral Florida. Ae albopictus and 14 other species of mosquitoes were collected from tires, flower-holding vases in cemeteries, other types of artificial containers, and treeholes. Ascogregarina taiwanensis (Lien & Levine) was the most common parasite of Ae. albopictus throughout the year. The microsporidium Vavraia culicis (Weiser) infected Aedes aegypti (L.), Ae. albopictus, Aedes triseriatus (Say), and Orthopodomyia sinifera (Coquillett). A vibrio bacterium and 2 fungi (Leptolegnia sp. and Smittium culisetae Lichtwardt), infected Ae. albopictus larvae but were observed infrequently. A. taiwanensis, S. culisetae, and the vibrio bacterium previously have been reported from Ae. albopictus. This is the 1st report of the other 4 microorganisms parasitizing Ae. albopictus larvae.

Data on tick control and knowledge of the damage caused to beef cattle by tick feeding were incorporated into a computerized dynamic life table model (LSTSIM) for Amblyomma americanum (L.). Simulations were made to determine economically feasible, 5-yr integrated pest management (IPM) strategies for A. americanum in forage areas utilized by Bos taurus, Bos indicus, and crossbred cattle (B. taurus x B. indicus). The effects of host resistance, pasture rotation, habitat conversion, topical acaricides, systemic acaricides, and the area-wide application of acaricides to pastures on populations of parasitic female ticks were simulated as individual control technologies and as components of multiple-factor IPM strategies. The most effective, single-factor control strategy for A. americanum in beef cattle forage areas is the use of tick-resistant B. indicus cattle. Pasture rotation combined with area-wide acaricide applications was the only economically feasible IPM strategy for B. indicus cattle and reduced tick densities by 89% after 5 yr. Thirteen economically feasible IPM strategies were identified for use with B. taurus cattle. Of these, the most efficacious was pasture rotation in May combined with systemic or topical acaricide applications. Other strategies included systemic acaricides with area-wide acaricide applications to pastures, topical acaricides with area-wide acaricide applications, pasture rotation with habitat conversion and topical acaricides, and pasture rotation with habitat conversion, topical acaricides, and area-wide acaricide applications. Each technology reduced tick densities on B. taurus cattle by > 80% over a 5-yr period. Nine IPM strategies were economically feasible for use with crossbred cattle. Of these, pasture rotation combined with systemic or topical acaricide applications reduced the number of female ticks on cattle by > 84%; pasture rotation combined with habitat conversion reduced tick numbers by 77%. The most effective nonacaricide-based IPM strategy for B. taurus and crossbred cattle was pasture rotation combined with habitat conversion. No acaricide-free IPM strategy was economically feasible for use with B. indicus cattle.

Updraft CDC traps baited with dry ice were used to monitor changes in the abundance and parity rate of Anopheles quadrimaculatus Say complex mosquitoes in an intermittently flooded swamp in Central Florida during an 18-d period. Mosquitoes collected each day were identified to species using DNA hybridization and isozyme electrophoretic techniques and were dissected to determine follicular maturation and parity. Of 1,178 An. quadrimaculatus mosquitoes identified to species, 4% were species A and 96% were species C. Dissections of females of both species indicated that 98% were nonblood fed and nongravid with ovariole development at Christophers' stage II. Overall parity rates were 0.19 and 0.51 for populations of species A and species C, respectively. The duration of the gonotrophic cycle for species C females was estimated to be 5 d based on the interval between peaks in the number of nulliparous females collected on days 1 and 6 and peaks in the number of parous females collected 5 d later. Significant trends were observed in the number of parous species C females collected each day, indicating that the parity rate could not be used as an unbiased estimator of survivorship.

A previous version of Lone Star Tick Simulation Model (LSTSIM) for a wildlife ecosystem was revised and expanded to include a beef cattle forage area and improved handling of tick-host-habitat interactions. Relationships between environmental and biological variables were also refined in the new version. General validity of the revised model was established by comparing simulated and observed host-seeking populations of Amblyomma americanum (L.) at five geographic locations, three in Oklahoma and two in Kentucky-Tennessee. Additional validity was indicated from comparisons of simulated and observed seasonality of lone star ticks at one location in Kentucky. The model produced acceptable values for initial population growth rate, generation time, and 15-yr population density when historical weather files for 14 locations in the United States were used. The model of A. americanum population dynamics was used to study the relationship between tick density and density of white-tailed deer, Odocoileus virginianus (Zimmerman), and cattle. The revised model can be used for additional simulation studies on effects of tick control technologies and integrated management strategies.

At least five groups of parameters regulate contact between ticks and host animals. Group 1 (seasonal effects) and group 2 (daily effects) comprise abiotic parameters and include daylength, temperature, relative humidity, and interactions thereof. Groups 3, 4, and 5 consist of biotic parameters. These pertain to biological processes in ticks (group 3), such as hunger responses and spatial patterns in aphagous tick populations; biological processes in host animals (group 4), such as patterns of habitat use by host animals; and interactions between host animals and ticks (group 5). Host-tick contact is possible when ticks are hungry, when ticks exhibit a positive appetence response, and when ticks and host animals are together in time and space. A descriptive model is proposed to correlate these processes and interactions with the observed behavior of the host-tick contact system in nature. Emphasis in the model is placed on host activity and differences among host types.

A project on management of lone star ticks, Amblyomma americanum (L.), at Land Between the Lakes, a Tennessee Valley Authority recreational area in Kentucky-Tennessee, during 1984-1988, demonstrated the effectiveness and economics of three control technologies. Acaricide applications (chlorpyrifos at 0.28 kg [AI]/ha), vegetative management (mowing and removal of 40% overstory and 90-100% of midstory, understory, and leaf litter), and host management (white-tailed deer exclusion from a 71-ha campground with a single-line fence) provided 75, 70, and 64% mean controls of all life stages of the lone star tick, respectively. Combinations of acaricide applications + vegetative management, acaricide applications + host management, and acaricide applications + vegetative management + host management produced 94, 89, and 96% mean control of all life stages, respectively. The costs of acaricide applications (two per year), vegetative management (two mowings per year), and white-tailed deer exclusion (single-line fence) were $45, $150, and $30/ha/yr, respectively. Results of this project are used to design management strategies that could be considered for use against lone star ticks in recreational areas.

To elucidate whether the luteinizing hormone-releasing hormone (LHRH) analog D-Trp6-Pro9-NEt-LHRH (LHRHa) decreases plasma testosterone levels in male primates solely by inhibiting gonadotropin secretion or, in addition, by inhibiting testicular testosterone biosynthesis, we have investigated the effects of this drug on 6 infant male rhesus monkeys. Three animals received LHRHa (12 micrograms . kg . day s.c., experimental group), and 3 animals received saline injections (control group) during the first 2 mo of life. Mean plasma testosterone was significantly lower in the experimental group compared to the control group (54 +/- 7 ng/dl vs. 501 +/- 52 ng/dl, P less than 0.001). The experimental group also had significantly lower mean follicle-stimulating hormone (FSH; 5.1 +/- 0.2 microgram/ml vs. 9.6 +/- 0.7 microgram/ml, P less than 0.001), and bioactive luteinizing hormone (LH; 2.0 +/- 0.08 microgram/ml vs. 3.5 +/- 0.2 microgram/ml, P less than 0.001). To study whether LHRHa influences testicular function directly, all animals were treated with human chorionic gonadotropin (hCG; 100 mIU . kg . day i.m.) for 28 days beginning at 8 mo of age. During Days 15 through 28 we administered LHRHa 12 micrograms . kg . day s.c. to the experimental animals and saline injections to the control group. Plasma testosterone increased to 5827 +/- 557 ng/dl in the experimental group and 4440 +/- 897 ng/dl in the control group after 14 days of hCG treatment. Plasma testosterone concentrations decreased in both groups of animals from Days 15 to 28 fo the study. All steroid intermediates were similar in both groups of animals on Days 14 and 28.(ABSTRACT TRUNCATED AT 250 WORDS)

Fertile females of a New World primate species, the squirrel monkey (Saimiri sciureus), have plasma progesterone concentrations that vary between 57 and 510 ng/ml during the reproductive cycle and are 10- to 20-fold higher than those seen in cynomolgus monkeys (Macaca fascicularis) and other Old World primates, including man. The plasma progesterone level during pregnancy is high and varies between 140 and 490 ng/ml. Estradiol levels during the reproductive cycle and pregnancy are also higher than those of cynomolgus monkeys. After 2-day treatment of ovariectomized monkeys with estradiol in oil, the progesterone receptor content in the uterine cytosol of the squirrel monkey is one eighth that in similarly treated cynomolgus monkeys [60.4 +/- 6.5 fmol R5020 bound/mg protein vs. 496 +/- 55 (mean +/- SE); n = 8]. The receptor affinity for R5020 is the same in both species. Thus, the elevated plasma progesterone levels in squirrel monkeys appear to be a compensatory response to a receptor-mediated decrease in sensitivity to progesterone. The squirrel monkey may be a model for the study of the mechanism of action and regulation of secretion of progesterone.

The location of Zebu, British, and Zebu x British cattle in tick-infested plots from March through September 1986 was compared with the location of Amblyomma americanum L. in the same plots. In April, May, and June, Zebu cattle spent less time (9.3-19.4%) in tick-infested quadrats than British (44.4-63.9%) or Zebu-British (49.0-69.3%) cattle. In the same months, the probability that A. americanum would contact Zebu cattle (1.5-19.6%) was significantly lower than for British (34.7-41.7%) or Zebu-British (30.2-56.9%) cattle. In April, May, June, and September, the probability that A. americanum detaching from cattle would drop into a quadrat presumed to be habitable for ticks was significantly lower for Zebu cattle (4.0-29.9%) than for British (64.9-72.6%) or Zebu-British (48.1-78.7%) cattle.

The extended feeding time response on cattle of adult lone star ticks, Amblyomma americanum (L.), during November through December is facultative and is mediated by the female. Mean feeding time (11.8 d) in female ticks taken from the field and held at 14:10 (L:D) photoperiod and 25 degrees C for greater than or equal to 15 d was significantly shorter (P = 0.05) than for females taken directly from the field and fed on cattle (14.6 d). Mean feeding times of females from the field paired to males from the field, males from the field held for 30 d at 14:10 (L:D) and 10 degrees C, or males from the field held for 30 d at 14:10 (L:D) and 25 degrees C were not significantly different (15.7, 16.3, and 16.2 d, respectively). When males from the field were paired with females from the field that had been held at 14:10 (L:D) and 10 degrees C or 14:10 (L:D) and 25 degrees C for 30 d, mean feeding time of the females was significantly longer (17.2 d) or shorter (14.0 d), respectively, than for all other groups.

Physicians often appear more troubled by moral dilemmas than would seem justified given the present social and professional consensus on many of the questions involved. Their discomfort arises not only at ethical, technical, and behavioral levels (the most commonly identified sources of difficulty), but also at an existential level, that is, as the manifestation of conflicts rooted in the processes and conditions of our coming-to-be as persons. Analysis of this level of physicians' moral difficulties requires renewed attention to the physician as a person, and suggests new perspectives on the interpersonal environment of medical practice.